GD&T Lesson 8: Position, Advanced Applications with Examples
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- čas přidán 15. 08. 2024
- I discuss several advanced applications of position from ASME Y14.5-2009.
I cover:
00:00 Intro
01:19 Threads
05:51 Counterbores
13:20 Patterns
19:09 Bi-directional Tolerance Zones
22:49 Coaxial Position Without Datum Reference
29:24 Repeated Pattern with Repeated Datum Reference Frame - Věda a technologie
I got through the GD&T Explained: Full Lessons playlist, and boy is this well done! Thank you for the lessons, really appreciate this!
Thanks so much!
Great series of videos sir, really learnt a lot of new stuff throughout the course. Thank you!
We do have MMC applied to thread positions on our drawing specifications. As an inspection function it is a real pain in the backside. We tend to have to use thread mics to determine external pitch diameters and coil wirers and gauge pins for internal.
Just finished the GD&T full lesson playlist. It's just amazing now I just wanna repeat lessons than dive into as much examples as possible. I also think you have other videos for some of the examples as well.
That’s great to hear! I have lots of videos detailing topics, as well as answering common questions. Feel free to leave any questions you have in the comments and I may be able to answer in a video.
This is awesome, here is guestion: you have a TP Dia .030 at MMB but you follow that with .035 MAX, so the hole tolerance would allow maybe .050 but with the MAX set at .035 is were your bonus stops, this could be used to control edge distance in sheet metal as a example.
Thank you for covering this. For position of tapped holes, I've had good results using the Tru-Pos threaded locators.
amazing sir! thank you for your time and consideration.
We do also use the conical tolerance control for very deep small diameter holes through beams. This allows for drill wonder through the part.
Thanks so much for sharing! Is there a reason for using the conical zone instead of a cylindrical zone set to the size of the larger size of the conical zone? Like I mentioned in the video, I’ve never seen it before, aside from the asme standards, so I’m curious about it’s application.
It is also helpful for sinker and wire EDM, watermelon, Laser and plasma cutting
this videos are great so much knowledge
Amazing video Mr. Odell Thanks for the detailed video.
Love your videos, thank you for making them.
As a mechanical design guy, I disagree with your recommendations on thread positions.
Using MMC on threads allows for inspection with a thread position gage, which threads into the hole. You should also project the tolerance over the length of the bolt. This makes the tolerance stackup work out functionally and allows you to maximize the tolerance.
Also, overriding ASME with the MINOR DIA callout is not a functional call out. There is a surprisingly large tolerance between the position of the pitch diameter and that of the minor diameter.
ASME has the defaults functionally correct for the vast majority of fixed fasteners. I'd recommend against overriding the defaults unless the function of the part lends itself to that. Rather, it's a better approach to focus on maximizing the functional tolerance values based on stackup analysis.
Dean, at 20:09 you mention with bidirectional tolerance zones that the axis of the hole can be tilted up to .060. However, in this example the axis can tilt diagonally as much as .067 (corner to corner). Just a minor point.
► Your videos are an asset to the GD&T community, keep up the good work!! ◄
How did you arrive at 0.067 when the horizontal and vertical are diametral tolerance zones?
The benefit of GD&T is that it takes rectangular +/- tolerance zone and circumscribe their hypotenuse which results in a diametral tolerance zone.
You treated both the horizontal diametral tolerance zone of 0.06, and the vertical diametral tolerance zone of 0.03 as if they were rectangular tolerance zones and then circumscribed their hypotenuse which resulted in 0.067.
@@jafo3814 Note the light blue rectangle that Dean drew to depict the tolerance zone. For an example, if the axis of a hole was located in the lower left at the back of the part and in the upper right at the front of the part, the axis would tile along the "hypotenuse" of the tolerance zone. I used the Pythagorean theorem to arrive at the .067.
@@christophersmith8621 Just because Dean has sketched the rectangle, it does not mean it was correctly shown, both zones are diametral. When you used the Pythagorean theorem to arrive at the .067 you used the 2 diametral zones as if they were 2 legs to your triangle.
The maximum horizontal tilt for the hole's axis is governed by the diametral zone of 0.06. If the axis is within 0.06, then the axis will be inspected for the vertical tilt governed by the diametral zone of 0.03. The 0.03 zone must be entirely within the 0.06 or parts thereof. The axis of the hole must meet both conditions otherwise it fails inspection.
@@jafo3814 See Y14.5-2018 §10.4.4. It discussed the shape of the tolerance zones for bidirectional position tolerancing.
@@christophersmith8621
I stand corrected, you are correct per ASME Y14.5 2018 §10.4.4. The example is a hybrid of positional and rectangular coordinate method. I wonder how many users actually use this method as opposed to §10.5.2.1?
I guess it is the designer's prerogative.
to be honest, i always assumed that the true position only applied to the hole and no one bothered to check the c'bore true pos, and i think a lot of people in the industry would think like me. I also think it would cost less to only put a FCF on the hole (instead of 1 on the hole and 1 on the Cbore) because it says 'don't bother to check the CBore' instead of pointing out the you want it inspected, especially when we talk with machine shops, and they tell us they eyeball the price by basically applying a flat rate per feature control frame.
same here, I've only been checking the true position for the thru-holes when they're shown like that on the print. None of the existing programs in our cmm have been checking the c'bores, either. Now I want to ask our machinists if they've been checking them out on the floor.
Very informative.
Thank you.
I wish you could make more videos on the ASME Certification test
We get thrown with drawings with threaded features and material modifications at my job all the time. Just recently I've been on the hunt for trying to figure out how to apply bonus to a tapped bore. Our inspectors have been rejecting potentially good parts because they've only been out of spec within a few thousandths that could potentially be saved with bonus tolerance if we just knew how to verify the actual measurement for pitch cylinder
These are awesome examples and well explained.
Thanks so much!
Awesome videos you make and I follow each one of them. Thank you. However, at segment 12:28 did you miss out on Datum-C to be added to the Flag for C'Bores - 4x?
Thanks so much! Yes, I made a mistake. It should be referenced to datum C
Great Video Dean! Thank you
Thanks so much! I hope it’s helpful.
thank you so much for this series
Wonderful video!
Thanks so much!
Hello Dean, thanks for the video.
For controlling the c/bore individually, the standard example shows C as the only datum in the FCF. Are both correct (the way you used it vs. the standard)? If yes, what's the difference?
Hi, you’re welcome! I made a mistake in drawing that figure on the board, it should be A & C, not A & B.
@@RDeanOdell Thank you.
datum c isn't called out out in any feature control frames on the 4x BHC at 11 min 24 sec so its irrelevant and not used in inspection its just a datum with no reference frame
thanks for the knowledge you shared.
I could see a conical tolerance zone maybe being useful for minimizing the control on a feature that only really needs to locate two interfaces at the interface plane. I am thinking maybe something like a wheel:hub interface on a car, where the centering ring is short and stubby and is only used for precisely aligning the wheel to the hub at the point of surface contact, and nothing more, since the wheel will ultimately be held on to the hub with lug bolts/nuts, which do not need the same type of control as the centering ring.
Thanks!
You’re welcome!
Hello Dean, what's the best way to locate a pair of threaded holes when they are datum B & datum C ? Because they are tight in tolerance, I belive they should be closed down by threads(precise in form), and use the cylinder of that threads to siumlate the datum B & C, is that correct?
In your last example, assuming there is a basic dim and connector line between the small hole and large, is the small hole constrained in translation vertically to D? if not, how?
Hi. Great videos. Learned a few new things or got a better understanding of some concepts, thank you. Would you be doing the same kind of course for ISO standard as well?
Thanks! Yes, I am working on some ISO GPS content.
Dean,
why don't you create a video over GD&T bad practices and mistakes which designers make
Hi,
I’ve always wanted to do a series where I review bad drawings and recommend corrections. The problem is no company is going to let me publicly criticize their work.
Maybe there’s a workaround, I’ll look into it.
Thanks for the suggestion! It’s a topic I want to cover, and it helps to have input.
@@RDeanOdell this sounds awesome. I wish I could throw drawings at you to use. But maybe recreating simpl examples similar to your lecture examples but show where people go wrong commonly?
Hey Dean! So there is job position open where only thing that i was not meeting requirement of is understanding of GD&T. Now that i went through these lessons and couple of more, could this be a good headstart to apply for that position or is there more that i have to go through. Of course i'm going to learn as much as possible, but i wanna apply ASAP
Hi, I think if you took notes and sketched a few parts and applied the GD&T, you would probably be okay with your interview if it requires an understanding of GD&T. It wouldn’t hurt to pick up a cheap used textbook and work through the problems.
@@RDeanOdell thank you for the response, this information means a lot because if i land an interview, i'll have plenty of time to analyze your videos and prepare. Great videos
17:45 How does this work? Would not the tolerance zone be a cylindrical shape about the basic bolt circle size and basic angle? If depicted like the lower left image at this timestamp, the tolerance zone would be the same size and relative position to its basic true position regardless of the number of rings or the circle's diameter. Only a toleranced angularity diverges over distance. Was this referencing only the GM manual example when you said "don't do this"?
Hi, thanks for the input! I should have erased what was behind me before I started talking about the next topic, the next topic is Bi-directional position where you can achieve square, rectangular or wedge shaped tolerance zones.
Starting at 10:05 should the CB have a CB symbol after the 4X and depth after the tolerance? And should the feature control frame include datum C or replace datum B with datum C?
Read thru the comments and got my answer about the datum.
Hi, yes I made a mistake on the board that I didn’t catch before making the video available.
you are best
Thanks so much for the vote of confidence! I’m happy you found my video helpful.
A short question: Shouldn't the B ref for the counterbore be C?
You are great
Thanks so much!
Hi I'm a student. Which book you recommend me only for blueprints,Drawings
Hi, I made a video about it:
GD&T Books for Students, Engineers, Drafters and Inspectors.
czcams.com/video/SdGSeD-KPgc/video.html
Do you have a CMM video for true position and profile? Let me know I want to see it and learn thank you
Hi, yes. I have a whole series of videos on Zeiss CMM programming including position & profile. It’s public & free, check my channel for access.
Hello, I am from India, my part has 9 holes on the face which is the datum A, 3 holes are in 1 PCD,3 are in another PCD, and 3 more are in another PCD, we got position tolerance 0.035 concerning datum A, we believe that this controls perpendicularity and how holes are away from each other, in this case, we need to consider all 9 holes together or only 3 holes of each PCD at a time?? if you give me the mail ID I can share the drawing ,
Dear sir can you recommend any good book that teaches you drafting?
At 10:00, should the position tolerance of counterbore refer to datum C instead of datum B(m)?
I think you are correct, hopefully Dean can confirm.
Curious for more info on the GM book you mention.
Hi, if you send your email address (I have a contact form in my website), I’d be happy to send over the PDF of the GM book.
can you add subtitle